Explosionproof switch box



Oct. 16, 1934. R H LLEY v 1,977,010

EXPLOSIONPROOF SWITCH BOX Filed July 19, 1955 INVENTOR.

' ATTORNEY5 Patented Oct. 16, 1934 1,977,010 ,EXPLOSIONPROOF swrron ox Raymond H. Olley, Syracuse, N. Y., assignor to Grouse-Hinds Company, Syracuse, N. Y., a core poration of New York "Application July 19, 1933, Serial No. 681,160 x I 15 Claims. (01. 247-18) This invention relatesto explosion proof electric conduit outlet boxes, and has for its object, a particularly simple and efiicient explosion proof means by which electric appliances, as switches,

45; can be readily applied to standard outlet boxes interchangeably with the explosion proof covers. for said boxes,.and also a means by which the switch can, be located in any position to conveniently locate; orto locate in a predetermined position, ,the operating member for the switch which is-located on the outer'side of the cap, or covenof the switch mechanism, which cap, or.

cover, is interchangeable with the usual cap or cover, for theoutletbox. By explosion proof is :qmeant a structure by which explosions occurring within the box are confined within the box. Ex-

plosions are liable to occur where there are explosive vapors, as gasoline vapors, in the surrounding atmosphere. v V

It is understood by. those skilled in the art that-explosion proof electrical fixtures are so constructed that should an explosionoccur within ,theqfixture, the ignited gaseswill be cooled below the ignition point of, the explosive gases in ;the atmosphere surrounding the fixture before they escape from within the fixture. It is common practice to attain this end in regard to joints between the various elements making up the fixturebyaccurately grinding the surfaces of the joints wherebythere, is a minimum of space at the'joints between the various elements so that there is a very small or thin passagefor the ignited gases to escape and accordingly, throughthe,

principle of mass action, a comparatively small ,amount of ignited gas comes in contact with the maximum surface of the metal whereby the gas is cooled. This-method-of forming joints is very effective. However, such grinding operations materially. increase the cost of thefitting, and due ,togexpansion and contraction, and the natural tendency of theiron'to warp these joints when groundaccurate at the factory very often lose their accuracyin a comparatively short timewith the result that the joint is no longer of such a -%'nature as to attainthe desired result.

An important objectjof' this invention is the provision of means whereby a switch, or-other electrical fixture, may 'be secured'into a stand ard conduit outlet'box, and'be secured inany --relative positionwithout the use of ground surfaces between the various elements. On account of the novel construction of my switch box I ob tain this result through the use of threadedfconnections, the threads forming a tortuouspath for the escape of the ignited gases which not only pro duces a' greater cooling efiect, but alsoIeliminates any possibility of the joints opening. upthrough warpage;expansion etc, U The invention consistsin the novelfeatures and in the combinations and constructions hereinafterset' forth and claimed.

In describing this invention, reference is had to the accompanyingdrawing in which like characters designate corresponding parts in all the views. a

Figure 1 is a plan view,'partly broken away, of a conduit outlet box provided with thisinvention.

Figure 2 is a longitudinal, sectional view. thereof.

Figure 3 is a sectional viewon line 33, Figure 1. a I a .1 designates a standard conduit outlet box which ishere shown as having a cylindrical body open at one end of the cylinder, and is provided with one or more nipples 2 for its connection to the electric conduit enclosing the service wires. .These boxes are-formed; for ordinary purposes,

withintern al threadedopenings 3,.for receiving the threads of a cover.

This, invention relates primarily to a switch mechanism supported by a cap interchangeable withthe usual cover.

Inthe illustrated embodiment of my invention, 3

the box is provided with an externally threaded isprovided with means for limiting the distance the collar 4 may thread into the threaded opening 3,-and also to; lock it from turning in either direction, and ashere shown a suitable snap ring 5 is provided for. this purpose, The construction of the snap ring forms no part of this invention.

6 designates acap forming part oftheswitch -mechanism, this threading: on the outer end of the collar 4, that'is, the end projecting out of the threaded. opening 3, and in use this cap is threaded down as tightlyas possible. Owing to r the threaded connection between thecap and collar, the cap is-applied to the box by a combined rotary and axial movement which may be.

eifected by means other than screw threads, as

a by bayonet joints.

'7 designates a, switch support, this" being swivelly connected tothe cap centrally, or concentrically therewith, and as here shown consists of aplate havingan arcuate wall 8 at one end, the plate being provided with suitable holes by means of which, the frameof aswitch S can be secured thereto, in any suitable manner, as by screws 9.

V The arcuate plate 8 acts as a shield to prevent the wires in the box from fouling on the switch operating member when the cap-is being screwed on the collar. As here shown, the plate is provided; with a hub 10 rotatably mountedin an axial passagein the cap 6 and held from axial: movement. 5 A switch. operating member is providedas a unit collar 4 externally threaded-throughout its length,

with the switch support and the cap, this being tended to sweep adjacent the arcuate wall 8, the

rock shaft extending outside of the cap and provided with an operating rock arm 13 at its outer end. I:

predetermined angle, regardless of the'number of turns it takes to threadthe cap 6-tightly in position, means is provided for locating the support in any radial angle, andholding-it from turning movement, but permitting axial movement thereof during the screwing and unscrewing of the cap ,6 on the collar 4, and as here shown, the support and'the collar are provided with slidably interlocking means consisting of tongues 16 and grooves 17 on the interior of the collar, and on the periphery of the support,tongues l8'on the support I interfitting with the tongues and grooves on the support, the tongues and grooves of the collar simulating splines.

When thebox is fixed in position in a conduit system, and the switch mechanism is to be applied, the desired angle of the operating arm 13 is determined after the arm 12 is interlocked with the switch lever L, or other operating means of the switch, and then the support is interlocked in the splines of the collar in the desired angular position. During the turning, or tightening of the cap obviously, the switch support 7 will not turn and also, the rock shaft 11 and operating arm 13 will not turn, as itis limited in its turning by the movement of the switch lever LL Thus,

when the cap is fully tightened, the lever 13' will be in its predetermined position. An adjustable indicator plate 14 to indicate the on and off f positions of the switch, and the operating'ar'm 11, is provided on the cover, this being an annular plate with the words on and off thereon,

and it being adjusted about the axis of the cap to define the throw of the arm 13 when in its on and"off position. Thisplatc l4-is held in its adjusted position in any suitable manner, as by screws here shown as two screws'l5 threading into holes in the cap with the heads lapping over the margin of the indicator 'plate,-b'ut' with the shanks of the screws clearing the plate. Thus by loosening the screws, the indicator plate can be shifted and held in its shifted position by tightening the screws.

Although I have shown an adapted collar in order to adapt the switch mechanism to standard switch or outlet boxes, nevertheless, it is apparent that the boxes may be initially formed with the collars integral therewith. What I claim is: 1. An electric conduit outlet box provided with a cylindrical externally threaded collar on one u side thereof enclosing an opening to the interior of the box, a cap threading on the collar, a switch support swivelled to the capcentrally thereof, and a switch operating member extending axially'of the swivel joint of the support to 'the outside of the cap,- the support and the box having means for'locating the support" in any radial angle, holding it from turning movement during the screwing'of the cap on the collar.

2. An electric conduit outlet box provided with la cylindrical externally threaded collar on one side thereof enclosing an ppeningto the in- L during the screwing of the cap on the collar.

. ,3. An electric conduit outlet box provided with a cylindrical externally threaded collar on one side thereof enclosing an opening to the interior of the box, a cap threading on the collar,

a switch support carried by the support as a unit therewith and swivelled to the cap centrally thereof, a switch operating member extending axially of the swivel joint of the support to the outside of the cap, the support and the box having means for locating the support in any radial angle, holding it from movement and permitting axial movement thereof with the cap during the screwing of the cap on the collar, and an adjustable indicator plate on the outer side of the cap for indicating the on and off positions of the operating member of the switch, said indicatorbeing adjustable to conform to the angular location of the switch support.

4. -An electric conduit outlet box provided with a cylindrical collar on one side thereof enclosing an opening to the interior of the box, a cap attachable to the collar for closing said opening by a combined rotary and axial movement, a switch support carried as a unit with the cap andswivelly connected to the cap centrally thereof and movable axially therewith, and. an

operating member for the switch extending outside of the cap, the switch support and the box having coacting meanswhich slidably interlock for locating the support in any radial angle and holding it from turning movement and permitting axial movement thereof during the movement of the cap relatively to the collar.

5. An electric conduit outlet box provided with a cylindrical collar on one side thereof enclosattachable to the collar for closing said opening by' a combined rotary and axial movement, a switch support carried as a unit with the cap and swivelly connected to the cap centrally thereof and" movable axially therewith, an operating member for the switch extending outside of the cap, the switch support and'the box having coacting means which slidably interlock for locating the support in any radial angle. and holding it from turning movement and permitting axial movementthereof during the movement of the cap relatively to the collar, said switch operating member extending axially of the swivel joint of I the support and being operable about its axis to off and on position, and an indicator plate on-the outer face of the cap and adjustable about the axis of the cap to locate the off and onpositions of the switch in accordance with the radialangle of the switch support.

ingan opening to the interior of the box, a cap 6. An electric conduit outlet box provided with a.cylindrical externally threaded collar on one side thereof enclosing an opening to the interior ing movement, a switch support swivelly connected to the cap centrally thereof, and an operating member for connection to the switch extending to the outside of the cap coaxially with v I v the swivel connection,'the collar and the support tenor of the box, a cap threading on the collar,

a switch support carried by the support as' aunit I therewith and. swivelled to the; cap centrally 5 thereof, anda switch operating member extend--- having interfltting tongues and grooves extending parallel to the axis of the cap for locating the support in any radial angle and holding it from turning movement andpermitting axial movement thereof during the attaching of the cap t the collar.

7. An electric conduit outlet box provided with a cylindrical collar on one side thereof enclosing an opening to the interior of the box, a cap for closing said opening attachable to the collar by a combined axial and turning movement, a switch support having a hub rotatably mounted in the cap centrally thereof, and an operating member for the switch on the support including a rock shaft mounted coaxially in said hub and extending to the outside of the cap, the support and the box having means for locating the support in any radial angle and holding it from turning movement and permitting axial movement thereof during the attaching of the cap to the collar.

8. An electric conduit 1 outlet box provided with a cylindrical collar on one side thereof enclosing an opening to the interior of the box, a cap for closing said opening attachable to the collar by a combined axial and turning movement, a switch support having a hub rotatably mounted in the cap centrally thereof, and an operating member for the switch on the support including a rock shaft mounted coaxially in said hub and extending to the outside of the cap, the support and the box having interfitting tongues and grooves extending parallel to the axis of the cap for locating the support in any radial angle and holding it from turning movement, and permitting axial movement thereof during the attaching of the cap to the collar.

9. An electric conduit outlet box provided with a threaded opening in one side, a collar threading into said opening and having means for limiting the movement of the collar into said threaded opening leaving a portion of the threaded collar projecting out of said opening, a capthreading on the projecting portion of the collar, a switch support swivelly carried by the cap centrally thereof, and a switch operating member extending coaxially of the swivel joint to the outside of the cap, the support and the collar having slidably interlocking means for locating the support in any radial angle and holding it from turning movement, and permitting axial movement thereof with the cap during the screwing on of the cap.

10. An electric conduit outlet box provided with a threaded opening in one side, a collar threading into said opening and having means for limiting the movement of the collar into said threaded opening leaving a portion of the threaded collar projecting out of said opening, a cap threading on the projecting portion of the collar, a switch support swivelly carried by the cap centrally thereof, and a switch operating member extending coaxially of the swivel joint to the outside of the cap, the support and the collar being formed with slidably interfitting tongues and grooves extending parallel to the axis of the collar for locating the support in any radial angle and holding it from turning movement and permitting axial movement thereof during the screwing of the cap on the collar.

11. An electric conduit outlet box provided with a threaded opening in one side, a collar threading into said opening and having means for limiting the movement of the collar into said threaded opening leaving a portion of the threaded collar projecting out of said opening, a cap threading on the projecting portion of the collar, 8. switch support swivelly carried by the cap centrally thereof, and a switch operating member extending coaxially of the swivel joint to the outside of the cap, the support and the collar having slidably interlocking means for locating the support in any radial angle and holding it from turning movement, and permitting axial movement thereof with the cap during the screwing on of the cap, the operating member for the switch being a rock shaft extending coaxially of said swivel joint and having a rock arm at its outer end, an indicator plate carried by the cap and adjustable about the axis thereof to conform to the radial angle of the switch support and indicate the on and off positions of said operating member.

12. The combination of a conduit electric outlet box provided with a threaded opening in one side, an externally threaded collar threaded into said opening, a portion of the collar projecting out of said opening, an internally threaded cap threaded on the projecting portion of the collar, a switch support rotatably mounted in said cap, said collar and the switch support having coacting means for locating the switch support in any one of a plurality of positions relative to the outlet box.

13. The combination of a conduit outlet box provided with an internally threaded opening in one side, an externally threaded collar, one end of said collar being threaded into said opening, and the other end projecting outwardly from said opening, an internally threaded cap threaded upon the projecting portion of the collar having its annular edge seated against the conduit outlet box, a switch support mounted centrally in said cap and having rotatable movement relatively thereto,

the collar and the switch support having means coacting to locate the switch support in any one of a plurality of positions relative to the collar,

and switch operating mechanism carried by the cap and operable from the outside thereof.

14. The combination of a conduit outlet box provided with a threaded opening in one side thereof, a collar threading into said opening with a portion of the collar projecting outside of the outlet box, an internally threaded cap threaded upon the projecting portion of the collar, a switch support journalled in said cap and having means coacting with the collar to secure the switch support in any one of a plurality of positions relatively to the collar, a switch secured to the switch support, switch operating mechanism carried by the cap and operable from outside of the cap to actuate the switch into on and off position, and a guard for said switch operating mechanism secured to the switch support and depending into the conduit outlet box.

15. The combination of an electric conduit outlet box provided with a threaded opening in one side, an externally threaded collar threading into said opening, a portion of the collar projecting out of said opening, an internally threaded cap threading on the projecting portion of the collar, a switch support suspended in the cap, a switch carried by the support and having operating means extending outside of the cap, the collar and the switch support having coacting means for locating the switch support in any one of a plurality of positions relative to the outlet box and for holding the switch support from turning during the threading on movement of the cap.

RAYMOND H. OLLEY. 

